As the conception of Carrier Ethernet (CE) is proposed, a connection-oriented Ethernet technology, Provider Backbone Transport (PBT), which satisfies the requirements of a telecommunication network emerged in October, 2005. After that, providers at home and abroad have adopted the PBT technology for networking, thereby offering a very good beginning for the development of the PBT technology in the Metropolitan Area Network (MAN).
The PBT technology is based on a Provider Backbone Bridge (PBB) technology defined by IEEE 802.1ah standard, wherein the IEEE takes the PBT technology as a Provider Backbone Bridge Traffic Engineering (PBB-TE) technology. The PBB-TE technology, which is based on the PBB technology and centered on improving the PBB technology, performs service forwarding by adopting an outer Media Access Control (MAC) address in combination with an outer Virtual Local Area Network (VLAN) identification, e.g. a Backbone Destination MAC Address (B-DA)+Backbone VLAN ID (B-VID), wherein the forwarding path is configured in advance. This is significantly different from forwarding a data message in a traditional Ethernet address learning way. By network management and control, services in the CE are made virtually connectively, so that the functions of the telecommunication network such as protection switching, Quality of Service (QoS), traffic engineering and the like can be realized. The PBB-TE technology is compatible with a framework of a traditional Ethernet bridge, and can forward data frames based on B-DA+B-VID without updating a network intermediate node or modifying the data frames, and the forwarding efficiency is high.
An attribute of a tunnel is represented as a triad of <ESP-DA, ESP-SA, ESP-VID>, in which ESP refers to a Ethernet Switching Path, the parameter ESP-DA refers to a Destination MAC Address of the Ethernet Switching Path, the parameter ESP-SA refers to a Source MAC Address of the Ethernet Switching Path, and the parameter ESP-VID refers to a B-VLAN value. A point-to-point Traffic Engineering Service Instance (TESI) is composed of a pair of bi-directional point-to-point ESPs. Specific descriptions associated with the triad and TESI can refer to the IEEE 802.1Qay standard.
FIG. 1 shows a schematic diagram of Ethernet tunnel protection as adopting the existing PBB-TE technology. To take a direction from left to right in FIG. 1 for an example, the ESP of the end-to-end working tunnel (i.e. Y-B-C-D-X) is <B-MAC2, B-MAC1 and B-VLAN1>. Wherein, B-MAC2 is the MAC address of X, that is the destination MAC address; B-MAC1 is the MAC address of Y, that is the Source MAC Address; and B-VLAN1 is the B-VLAN value of Y-B-C-D-X.
In the prior art, 1:1 end-to-end protection of the tunnel has been implemented. As shown in FIG. 1, in the end-to-end working tunnel Y-B-C-D-X of the TESI, Y and X are endpoints of the tunnel instance; Y-F-G-H-X is an end-to-end backup tunnel of the TESI, that is, Y-F-G-H-X is the backup tunnel of Y-B-C-D-X. Wherein, Y-B-C-D-X is a bi-directional end-to-end working tunnel, and Y-F-G-H-X is a bi-directional end-to-end backup tunnel. Furthermore, a group of a working tunnel and a corresponding backup tunnel is constituted by a pair including the middle solid line along Y-B-C-D-X and the middle dashed line along Y-F-G-H-X; and another group of a working tunnel and a corresponding backup tunnel is constituted by a pair including the thick solid line along Y-B-C-D-X and the thick dashed line along Y-F-G-H-X. Therefore, when a fault is detected on Y-B-C-D-X, both the directions can be switched to Y-F-G-H-X. In order to distinguish whether a message is forwarded on the working tunnel or the backup tunnel, during configuration in advance, Virtual Local Area Network identifications (B-VLAN) carried by the tunnels are respectively specified for the working tunnel and the backup tunnel, for example, B-VLAN1 is specified for the working tunnel, and B-VLAN2 is specified for the backup tunnel.
The continuity of a tunnel is detected by sending a Continuity Check Message (CCM) via the tunnel, wherein the CCM is defined in the IEEE 802.1ag standard. The endpoints of the tunnel send the CCM to each other along the working tunnel and the backup tunnel respectively, and B-VLAN1 and B-VLAN2 are respectively encapsulated in message headers of the CCMs along the working tunnel and the backup tunnel. This can refer to the IEEE 802.1Qay standard.
When a tunnel traverses a very weak or very important path, protection can be performed only for a physical or logical path, or a locally physical or locally logical path of the end-to-end tunnel, which should be collectively called as path protection below without distinction. Path protection in the PBB-TE network can protect all tunnel instances carried on the path. The combination of the path protection and the 1:1 end-to-end tunnel instance protection can enhance the robustness of the PBB-TE network, enhance the speed of fault recovery, and reduce nodes involved in protection switching.
As shown in FIG. 2, which shows a schematic diagram of path protection of a Ethernet tunnel, B-C-D is an end-to-end working tunnel, namely a bearing path of TESI-1, TESI-2 and TESI-3. Wherein, the protected objects are TESI-1 and TESI-2; B-C-D is a working path; and B-F-G-H-D is a protection path for the working path. The working path and the protection path constitute a path protection group. Namely, B-C-D is a working entity, and B-F-G-H-D is a protection entity for B-C-D. TESI-1 and TESI-2 are respectively configured as the protected objects of the path protection group at the endpoints B and D. When fault happens on the working entity B-C-D, TESI-1 and TESI-2 on the working entity of the protection group are switched to the protection entity. In FIG. 2,  refers to the protection group; TESI-1, TESI-2 and TESI-3 are respectively represented as different thick solid lines, wherein TESI-3 is the thickest, TESI-2 is the middle, and TESI-1 is the thinnest; and bridge equipments are represented as .
It is supposed that when protection switching is performed for a TESI protected in a PBB-TE network, protection switching is implemented by adopting a selected optimum outbound port, based on configured outbound ports and in conjunction with a corresponding protection switching mechanism selected in different status detection scenes, so that the protection switching can be implemented as soon as possible, thereby enhancing the speed of fault recovery, reducing nodes for the protection switching, being beneficial to network optimization, and ensuring the reliability of end-to-end traffic. However, such a solution does not exist at present.